Cellulosic products



G. B.OLSON CELLULOSIC PRODUCTS March 10, 1964 Filed June EQ. 1960 United States Patent Ofi .Lice

3,124,l35 Patented Mar'. l0, 1954 3,124,135 CELLULOSIC PRODUCTS George B. Olson, Niles, Mich., assigner to Kimberly- Clark Corporation, Neenah, Wis., a corporation of Delaware Filed .lune 30, 1969, Ser. No. 39,935 3 Claims. (Cl. 12S-290) This invention relates broadly to improvements in absorbent bandages and particularly to bandages of the sanitary napkin type.

A major object is to provide a sanitary napkin of a construction which substantially prevents strike-through of dark-colored portions of menstrual fluid thus minimizing the danger of soiling undergarments during the menses.

Another object is to provide an improved napkin having incorporated therein an element which effectively segregates the darker colored portion of the menstrual discharge.

An additional object of the invention is to provide an improved sanitary napkin having incorporated therein an element containing a functional chemical reagent.

Still another object is to provide a sanitary napkin of a construction which promotes eflicicnt utilization of available absorbent capacity.

Other objectives and advantages will become apparent from the drawings and description as will various modifications and adaptations of the described structure without departure from the inventive concept as defined in the appended claims.

FIG. l is a perspective view of a sanitary napkin shown partially open to illustrate incorporation therein of the inventive principles.

FIG. 2 is a cross section taken on line 2-2 of FIG. l.

FIG. 3 is a view similar to FIG. 2 but illustrating a sanitary napkin of modified construction.

Sanitary napkins in the course of their development have become a necessary part of feminine hygiene, and have been progressively improved both as a result of consumer demand and the highly competitive nature of the market. While substantial improvements in design have been made, and are continuing, it is generally recognized that results still fall short of obtaining What might be defined as the ideal product. An optimum design ideally incorporates such characteristics as softness, retention of form during use, efficient liquid absorption, and ability to resist strike-through and concomitant bottom and side stains, even when the napkin is subjected to excessive quantities of fluid and abnormal pressures during use.

This invention is particularly directed to improving the construction of sanitary napkins in a manner to minimize the problem of bottom-staining caused by the abovementioned strike-through without adversely affecting other desirable properties, and actually enhancing some of the latter. Previous means used in the attempt to prevent bottom-staining include: The incorporation of various uid resistant baffles located internally of the pad; fiuid impervious barriers located at the bottom side of the pad; and additions to the total amount of material in the pad to increase available absorptive capacity. While these remedies were effective in eliminating certain problems they often inadvertently introduced others. For example, some of the constructions result in onesided napkins which are ineffective when Worn improperly. Others prevent the escape of water vapor because of inadequate ventilation and thus may cause a feeling of discomfort when Worn. Still others increase the over all cost of the napkin, making it relatively uneconomical to both producer and user.

The present invention minimizes strike-through of darkcolored portions of the menstrual iiuid virtually to eliminate bottom-stains While more effectively utilizing the available absorbent capacity of the napkin.

These improvements are obtained by providing in the body of the absorbent pad a control element containing a protein reactive chemical. When menstrual fluid entering the pad reaches the control element any proteinaceous materials in the fluid, especially highly colored hemoglobins, are agglomerated or precipitated in situ by the chemical-containing element. The precipitated proteinaceous material is retained on and in the control element by an adsorptive filtering action and thus only that part of the fluid which is relatively colorless is permitted to pass therethrough for absorption in other portions of the pad. If this relatively colorless watery fluid, after passing through the chemically treated elements, should accumulate in sufhcient quantity to reach the bottom of the pad, it results in virtually no stain. Thus, the pad user may wear pads of this improved construction secure in the knowledge that the possibility of embarrassing stains occurring is practically non-existent. This confidence in the effectiveness of sanitary protection engenders a sense of composure on the part of the user which is of immeasurable psychological value during menses.

The protein reactive chemical obviously must be nontoxic and non-irritating, and must effect the precipitation quickly and efficiently to insure that all the colored material coming in contact with the chemical containing element is precipitated out. The chemical must also be capable of being introduced into a soft absorbent element such as cellulose Wadding, flufl, cotton fiber batts, or the like, Without imparting to the element undesirably low softness or absorbency properties. Non-toxic salts containing multivalent ions have proved most effective for this purpose. Included in the group of salts found useful are, for example, ferric ammonium sulfate, ferric sulfate, aluminum zinc sulfate, aluminum potasasium sulfate, aluminum sodium sulfate, aluminum ammonium sulfate, aluminum sulfate, ammonium sulfate, aluminum acetate, zinc acetate, zinc ammonium sulfate, and zinc carbonate. Other salts such as certain phosphates and the like previously known for their use in salting-out proteins when preparing various pharmaceutical compounds, may also be used in the control element With varying degrees of efficiency. Of the salts listed above, ferric ammonium sulfate has been found to be the most suitable.

While various elements within the pad itself may be treated with the protein-precipitating material, the treated element preferably is located interiorly of the pad with sufficient absorbent material positioned exteriorly on opposite sides thereof to absorb fluid both before and after passage through the treated element. Such a napkin will absorb any excess of the essentially decolorized fluid which may pass through the treated element under severe conditions.

As shown in FIGURES 1 and 2, a pad body 4 may comprise top and bottom or outer face layers 6, 6 of a plurali-ty of plies of absorbent creped tissue known as cellulose wadding. inwardly of the cellulose wadding layers 6, 6 are layers of loosely felted fibrated wood pulp material 8, 8, commonly known as fiuff. The thickness and composition of each of these absorbent layers may vary considerably and may be interchanged in position or have one or the other type omitted depending on how much total absorbent capacity and softness is designed into the pad. intermediate the iiu layers 8, S is an element 7 impregnated with a protein-precipitating chemical. The entire pad structure is enclosed in the usual liuid permeable wrapper 9 which has end extensions forming attachment tabs in the usual manner.

The modified structure of FIG. 3 includes two impregnated elements 7 located interiorly of the pad. It is understood that the location of element or elements 7 within a pad may be varied without departing from the inventive principles herein described.

When the napkin is worn in the proper position, the overlapping portions of the wrapper 9 are located on the side of the pad not in contact with the body. However, if the pad position is inadvertently reversed and worn improperly, it will still function effectively since the control element works equally well with fluid ow in either direction.

When menstrual fluid is delivered to the napkin, it rapidly penetrates the pervious wrapper and to a large extent is absorbed in the top layers of absorbent cellulose wadding and fluff. As the volume of flow increases some f the iluid eventually migrates through the upper layers of the pad to the impregnated element 7 where a rapid chemical reaction between the proteinaceous material in the fluid and the salt in the element takes place. The hemoglobin and other proteins are precipitated out almost immediately and form a layer of gelatinous bead-like particles. As the gelatinous layer accumulates on or near the surface of chemically treated element 7, uid migration through the element is restricted in the area of accumulation, and that area acts as a bafe or equalizer to promote lateral migration of fluid through the adjacent absorbent layer and along the surface of the control element. The increased lateral ow thus utilizes more of the pads available absorbent capacity while permitting Y additional areas of the impregnated element to react with the proteins in the fluid.

Fluid penetrating the treated element is rendered relatively colorless by the salting-out action and subsequent removal of the highly colored hemoglobins. Thus, if any of the residual uid reaches the bottom of the pad during periods of eXtra heavy ow, little visible staining results since the residual watery fluid is relatively colorless.

Because the available absorbent capacity of the pad also is more effectively utilized, it can readily be seen that to retain comparative amounts of fluid discharge in pads of this improved construction, less absorbent material is needed than is ordinarily required, thus realizing substantial savings in manufacturing costs.

It has been found that even when relatively minor amounts of suitable salts are present in the element some protein precipitation does take place. However, in order to insure efficient precipitation of the protein present in normal menstrual discharge, it is preferred that the salts be present in an amount by weight at least equal to the dry weight of the fibers present in the element to be impregnated. For example, control elements were prepared from creped wadding sheets measuring about 211/16 x 5" and weighing about 0.2 gram before impregnation. Selected sheets were impregnated with about 0.2, 0.5, 0.8 and 1.0 gram of ferrie ammonium sulfate, respectively. Each of the samples was then given both bench and clinical tests. It was found that elements containing the larger concentrations of salt precipitated the proteins out more rapidly and efficiently than those with smaller concentrations. latter, the amount of penetration by the dark-colored hemoglobins was considered negligible, hence performance in accordance with the invention was satisfactory.

However, even with the 6 When the control element is impregnated with one of the aforementioned salts there may be a tendency for the element to become somewhat stili and brittle. This condition is eliminated by adding to the salt solution, or to the previously impregnated element, a compatible nontoxic plasticizer such as polyethylene glycol, glycerine, or the like. A 5% solution of the plasticizer is sufficient to give the impregnated element a permanent softness and elasticity suitable for use in absorbent pads.

The element itself may consist of any suitable absorbent material such as one or several plies of absorbent creped tissue, cellulose wadding, wood fiber pulp, regenerated cellulose sponge, brous non-woven webs, surgical gauze, or the like.

Various changes in the described structure may be made without departing from the principles of the invention.

What is claimed is:

1. A sanitary napkin comprising multiple layers of absorbent elements, at least one of said elements having uniformly distributed therethrough a non-toxic proteinprecipitating salt in an amount by weight at least equal to about the dry weight of the absorbent material in said element, said salt-containing element being positioned interiorly of said pad whereby dark-colored portions of menstrual uid absorbed therein during normal use are precipitated out and retained interiorly of said napkin.

2. A sanitary napkin comprising an absorbent pad and a iluid pervious wrapper enclosing said pad, said pad comprising multiple layers of absorbent elements, at least one of said elements having uniformly distributed therethrough a non-toxic protein-precipitating salt and a plasticizer, said salt being present in said element in an amount by weight at least equal to about the dry weight of the absorbent material in said element, said salt-containing element being positioned interiorly of said pad whereby dark-colored portions of menstrual fluid absorbed therein during normal use are precipitated out and retained interiorly of said pad.

3. The sanitary napkin of claim 2 in which the proteinprecipitating salt is ferric ammonium sulfate and the plasticizer is polyethylene glycol.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES U.S. Dispensatory, 25th ed., page 1689. Scientific Library.)

Chemistry and Manufacture of Cosmetics, De Navarre, pages 261-262, (Copy in Div. 43.)

(Copy in 

1. A SANITARY NAPKINS COMPRISING MULTIPLE LAYERS OF ABSORBENT ELEMENTS, AT LEAST ONE OF SAID ELEMENTS HAVING UNIFORMLY DISTRIBUTED THERETHROUGH A NON-TOXIC PROTEINPRECIPITATING SALT IN AN AMOUNT BY WEIGHT AT LEAST EQUAL TO ABOUT THE DRY WEIGHT OF THE ABSORBENT MATERIAL IN SAID ELEMENT, SAID SALT-CONTAINING ELEMENT BEING POSITIONED INTERIORLY OF SAID PAD WHEREBY DARK-COLORED PORTIONS OF MENSTRUAL FLUID ABSORBED THEREIN DURING NORMAL USE ARE PRECIPITATED OUT AND RETAINED INTERIORLY OF SAID NAPKINS. 